package demo8;

/**
 * Created by Administrator on 2017/4/6.
 */
//: MapPerformance.java
// Demonstrates performance differences in Maps

import java.util.*;

public class MapPerformance {
    private static final int REPS = 200;

    public static Map fill(Map m, int size) {
        for (int i = 0; i < size; i++) {
            String x = Integer.toString(i);
            m.put(x, x);
        }
        return m;
    }

    private abstract static class Tester {
        String name;

        Tester(String name) {
            this.name = name;
        }

        abstract void test(Map m, int size);
    }

    private static Tester[] tests = {
            new Tester("put") {
                void test(Map m, int size) {
                    for (int i = 0; i < REPS; i++) {
                        m.clear();
                        fill(m, size);
                    }
                }
            },
            new Tester("get") {
                void test(Map m, int size) {
                    for (int i = 0; i < REPS; i++)
                        for (int j = 0; j < size; j++)
                            m.get(Integer.toString(j));
                }
            },
            new Tester("iteration") {
                void test(Map m, int size) {
                    for (int i = 0; i < REPS * 10; i++) {
                        Iterator it = m.entrySet().iterator();
                        while (it.hasNext())
                            it.next();
                    }
                }
            },
    };

    public static void test(Map m, int size) {
        // A trick to print out the class name:
        System.out.println("Testing " +
                m.getClass().getName() + " size " + size);
        fill(m, size);
        for (int i = 0; i < tests.length; i++) {
            System.out.print(tests[i].name);
            long t1 = System.currentTimeMillis();
            tests[i].test(m, size);
            long t2 = System.currentTimeMillis();
            System.out.println(": " +
                    ((double) (t2 - t1) / (double) size));
        }
    }

    public static void main(String[] args) {
        // Small:
        test(new Hashtable(), 10);
        test(new HashMap(), 10);
        test(new TreeMap(), 10);
        // Medium:
        test(new Hashtable(), 100);
        test(new HashMap(), 100);
        test(new TreeMap(), 100);
        // Large:
        test(new HashMap(), 1000);
        test(new Hashtable(), 1000);
        test(new TreeMap(), 1000);
    }
} ///:~
